chore(deps): update postgres docker tag to v16.8

Author: renovate[bot]

stack/docker-compose.yml

@@ -2,7 +2,7 @@ name: refarch-stack
 
 services:
   postgres:
-    image: postgres:16.4-alpine3.20@sha256:5660c2cbfea50c7a9127d17dc4e48543eedd3d7a41a595a2dfa572471e37e64c
+    image: postgres:16.8-alpine3.20@sha256:951d0626662c85a25e1ba0a89e64f314a2b99abced2c85b4423506249c2d82b0
     environment:
       - POSTGRES_DB=postgres
       - POSTGRES_USER=admin
@@ -67,7 +67,7 @@ services:
     security_opt: *security_settings
 
   db-postgres-keycloak:
-    image: postgres:16.4-alpine3.20@sha256:5660c2cbfea50c7a9127d17dc4e48543eedd3d7a41a595a2dfa572471e37e64c
+    image: postgres:16.8-alpine3.20@sha256:951d0626662c85a25e1ba0a89e64f314a2b99abced2c85b4423506249c2d82b0
     environment:
       - POSTGRES_DB=keycloak
       - POSTGRES_USER=keycloak-user